Fix Robot Arm Keep Exact functionality with item pipes

[BryanSer]

What

Fixes #2799
This PR fixes an item count calculation issue in RobotArmCover's KEEP_EXACT transfer mode. The previous implementation didn't properly verify if the items being moved matched the target slot's contents, leading to incorrect item quantity returns.

Implementation Details

• Removed the redundant isStackSpecific parameter from countStack method
• Revised item matching logic to require both:
  • ItemStack matching (using ItemStackHashStrategy.comparingAllButCount)
  • Filter test from RobotArmCover
• Simplified conditional checks in item counting logic

Outcome

• Correctly verifies item type matches before counting items in destination container
• Ensures RobotArmCover's KEEP_EXACT mode only counts matching items that pass its filter

[omergunr100]

logic looks good but run spotlessApply

[BryanSer]

I'll fix it tonight, thanks for feedback.

[umajho]

I can confirm that KEEP_EXACT works with multiple filtered items now. Thank you.
I believe that this fix will benefit processing line design a lot. I'm gonna replace the jar included in the modpack I'm playing with the one built from this PR immediately, so that I don't need to wait for the next release.